Such construction machines are known in practice. The sensor units serve to monitor various operational parameters of the construction machine and the work result thereof. Moreover, on the basis of the data gained, various operational parameters of the construction machine can be adapted for achieving a work result that is as good as possible.
Some sensor units of such types are based on sensing an external reference. These may e.g., be existing structures on the site, a wire or a laser reference, as is e.g., disclosed in US 2004/0068896 A1 or U.S. Pat. No. 5,917,593 A. To ensure a proper function during operation, such sensor units have to be set up prior to operation such that they are able to detect the position of the external reference as accurately as possible. To this end the sensor unit is arranged on the construction machine such that the external reference is located during operation in an area in which the sensor(s) of the sensor unit can detect it as accurately as possible. For a long time this process has been carried out by the operating personnel exclusively by hand. For this purpose the measurement range of the sensor unit, e.g. a distance from a sensor, had to be known. For instance, the sensor unit was oriented relative to the external reference and the distance between the two was checked with a yardstick.
In the meantime, however, there are also construction machines comprising setup assistance systems for sensor units. Most of the times, these are sensor units for detecting a plane reference defined by a rotation laser. The laser sensor will be shifted in vertical direction until the rotation laser hits as centrally as possible on the sensor area. The operator is informed by LED's whether the receiver has to be shifted upwards or downwards. Some of these systems also employ a motorized or automated shifting of the receiver.
Such conventional setup assistance systems have the disadvantage that they are exclusively suited for the setup of sensors that detect a planar reference, such as e.g., a plane formed by a rotation laser. Sensor units for linear references, such as e.g., a static laser beam, can be set up only inadequately with the existing systems.